Metal solutions, carrier added reactions

Diastereomer ratios were determined by gas chromatography. Since the aldol adduct undergoes retroaldol reaction on the column, it must be silylated prior to injection. Approximately 5 mg of the crude adduct is filtered through a short plug of silica gel to remove any trace metals. The material is taken up into 1-2 mL of dichloromethane in a 2-raL flask or small test tube. To this solution are added 4-5 drops of N,N-diethyl-1,1,1-trimethylsilylamine and a small crystal of 4-(N,N-dimethylamino)pyridine (Note 11), The solution is stirred for 2 hr and injected directly onto the column. (Column conditions 30 m x 0.32 mm fused silica column coated with OB 5, 14 psi hydrogen carrier gas, oven temperature 235°C). 

The linking of a metal to an antibody could, in principle, be accomplished by forming the metal chelate either prior to or after attachment to protein. Success to date has been achieved only by formation of the protein-ligand conjugate before metal chelation. The complexation reaction has several general features. First, reactions between the metallic radionuclides and antibodies are almost always performed with sub-stoichiometric quantities of chelate and metal ion. It is therefore of the utmost importance that no carrier added metals obtained from commercial sources be exceedingly pure or else be purified prior to use. Reactions of "carrier added" metal solutions are not likely to be of use because of the ease with which available chelate sites become saturated. Because the formation of chelate complexes is usually a bimolecular reaction, the complexation will proceed optimally when more chelation sites are available. Similarly, the more isotope in solution, the faster the reaction. Employment of a carrier chelate to insure solubilization of the radiometal is of value to maximize available isotope and the acetate ion has proven useful. 

The electrochemical procedure for the synthesis of the complex was similar to those described by Tuck [559]. The cell was a 100-cm3 tail-form beaker fitted with a rubber bung through which the electrochemical leads enter the cell. The indium anode was suspended from a platinum wire and the cathode was a platinum wire. [(pySe)2] (0.31 g) was dissolved in acetonitrile and a small amount of tetraethylammonium perchlorate was added to the solution as a current carrier. An applied voltage of 10 V produced a current of 15 mA. During the electrolysis nitrogen gas was bubbled through the solution to provide an inert atmosphere and also to stir the solution phase. After 1 hr of reaction 70 mg of metal had been dissolved from the anode (Ey = 1.1). 

The absorption of ozone by cyanide solutions in stirred reactors is complicated by mass transfer considerations. The presence of ozone gas in the exhaust from such a reactor does not indicate that equilibrium has been obtained between ozone gas bubbles and ozone in solution, but rather that the mass transfer through the individual bubbles is not complete, because of the resistance on the gas side. In other words, mass transfer controls the reaction, as the ozone will react almost instantaneously with the cyanide ion in solution. The presence of some metals, particularly copper, appears to speed up the absorption by acting as oxygen carriers. A solution of ozone in dilute acid decomposes somewhat more quickly when a trace of cupric ion is added. The presence of these metal catalysts, if this be their function, does not appear to be a necessary condition to ozone oxidation. What is important is that adequate mass transfer time and surface be available, as would be found in a countercurrent packed tower. 

For many of the metals generated by one of the three general methods in the preceding text, the finely divided black metals will setUe after standing for a few hours, leaving a clear, and in most cases colorless, solution. This allows the solvent to be removed via a cannula. Thus the metal powder can be washed to remove the electron carrier as well as the alkali salt, especially if it is a lithium salt. Moreover, a different solvent may be added at this point, providing versatility in solvent choice for subsequent reactions. 

Bethge and Lindstroem [49] first removed metal cations from a IQmL sample of water by elution with water from a Dowex 50W-X8 ion exchange column and the eluate was titrated to pH8 with standard tetra-butylammonium hydroxide. A calculated amount (as determined from the titration) of hexanoic acid was added as internal standard, the solution was concentrated to a syrup, the syrup was dissolved in acetone, and a-bromotoluene was added in slight excess. After 2h to ensure complete reaction, IpLof the acetone solution was injected into a stainless steel column (2m x 2mm) packed with 3% of butane-l,4-diol succinate with nitrogen (30ml min ), as carrier gas and flame ionisation detection... 

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